A technique is presented for correcting phase distortion in a digital wireless transmitter. The technique includes: receiving an RF signal in an analog domain by a digital-to-RF modulator; amplitude modulating, the RF signal in accordance with a digital input code; and introducing delay in a signal path traversed by the RF signal before the digital-to-RF modulator using a delay circuit. The duration of the delay depends upon the value of the digital input code and substantially cancels out the phase distortion introduced by the digital wireless transmitter.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for correcting phase distortion in a digital wireless transmitter, comprising: receiving, by a digital-to-RF modulator, an RF signal in an analog domain; amplitude modulating, by the digital-to-RF modulator, the RF signal in accordance with a digital input code; introducing, by a delay circuit in the analog domain, delay in a signal path traversed by the RF signal before the digital-to-RF modulator, where the duration of the delay depends upon the value of the digital input code and substantially cancels out the phase distortion introduced in the digital wireless transmitter.
2. The method of claim 1 further comprises determining an amount of phase distortion introduced into a modulated signal output by the digital transmitter, where the amount of phase distortion varies continuously with value of the digital input code.
3. The method of claim 2 further comprises determining an amount of phase distortion for at least two modulated signals and computing a slope for the phase distortion from the amount of phase distortion determined from the at least two modulated signals, where the at least two modulated signals are each modulated with different digital input codes.
4. The method of claim 2 further comprises determining an amount of phase distortion for a plurality of modulated signals, where each modulated signal in the plurality of modulated signal is modulated with a different digital input code selected from a set of possible digital input codes.
5. The method of claim 1 further comprises determining the phase distortion introduced into a modulated signal output in the digital transmitter; segmenting the phase distortion in multiple segments; and implementing a different delay component for each segment of phase distortion, where the delay circuit includes a delay component for each segment of phase distortion.
6. The method of claim 1 further comprises receiving, by a controller, value for the digital input code, and adjusting delay introduced by the delay circuit in accordance with the value for the digital input code.
7. The method of claim 1 further comprises arranging the delay circuit in a signal path traversed by phase component of the RF signal, where the RF signal includes only one phase component.
8. The method of claim 1 further comprises arranging a delay circuit in a signal path traversed by each phase component of the RF signal, where the RF signal includes two or more phase components.
9. A digital wireless transmitter, comprising: a digital-to-RF modulator configured to receive the RF signal and amplitude modulate the RF signal in an analog domain in accordance with a digital input code; and a delay circuit disposed before the digital-to-RF modulator, wherein the digital-to-RF modulator is configured to receive the RF signal and introduce a delay in the RF signal such that duration of the delay introduced by the delay circuit depends upon the value of the digital input code and substantially cancels out phase distortion introduced by the digital-to-RF modulator in the digital transmitter.
10. The digital wireless controller of claim 9 further includes a controller interfaced with the digital-to-RF modulator and the delay circuit, wherein the modulator circuit amplitude modulates the RF signal in accordance with the digital input code received from the controller, and the controller adjusts to the delay introduced by the delay circuit in accordance with the digital input code.
11. The digital wireless transmitter of claim 9 implements modulation of the RF signal such that the delay circuit is arranged in a signal path traversed by a phase component of the RF signal.
12. The digital wireless transmitter of claim 9 further comprises arranging a delay circuit in a signal path traversed by each phase component of the RF signal, where the RF signal includes two or more phase components.
13. The digital wireless transmitter of claim 9 further comprises a plurality of delay circuits in parallel before the digital-to-RF modulator, such that the duration of delay introduced by each of the plurality of delay circuits differs.
14. The digital wireless transmitter of claim 9 further comprises a plurality of delay circuits in series or in parallel before the digital-to-RF modulator, such that phase distortion introduced in the digital transmitter is segmented into multiple segments and each delay circuit in the plurality of delay circuit corresponds to a different segment of phase distortion introduced in the digital transmitter.
15. The digital wireless transmitter of claim 9 wherein the delay circuit includes a buffer in series with a capacitor bank and a controller interfaced with the capacitor bank, wherein the capacitor bank includes a plurality of capacitors arranged in parallel, and a switch electrically coupled to each capacitor in the plurality of capacitors, such that switches are controlled by the controller.
16. A digital wireless transmitter, comprising: a rectangular-to-polar converter circuit configured to receive an RF carrier signal; a phase modulator circuit configured to receive a phase component of the RF carrier signal from the rectangular-to-polar converter circuit; a RF digital-to-analog converter circuit configured to receive an amplitude component of the RF carrier signal from the rectangular-to-polar converter circuit and the modulated phase component of the RF carrier signal from the phase modulator circuit, wherein the RF digital-to-analog converter circuit operates to amplitude modulate RF carrier signal in accordance with a particular digital input code; and a delay circuit disposed along a signal path before the RF digital-to-analog converter circuit, where duration of the delay introduced by the delay circuit depends upon the value of the particular digital input code and substantially cancels out phase distortion introduced in the digital transmitter.
17. The digital wireless transmitter of claim 16 wherein the RF digital-to-analog converter circuit further includes a decoder and a series of power amplifiers.
18. The digital wireless transmitter of claim 16 further includes a controller interfaced with the RF digital-to-analog converter circuit and the delay circuit, wherein the RF digital-to-analog converter circuit amplitude modulates the RF carrier signal in accordance with the particular digital input code received from the controller and the controller adjusts to the delay introduced by the delay circuit in accordance with the particular digital input code.
19. The digital wireless transmitter of claim 16 wherein the delay circuit includes a buffer in series with a capacitor bank and a controller interfaced with the capacitor bank, wherein the capacitor bank includes a plurality of capacitors arranged in parallel, and a switch electrically coupled to each capacitor in the plurality of capacitors, such that switches are controlled by the controller.
20. The digital wireless transmitter of claim 16 further comprises a plurality of delay circuits, such that phase distortion introduced in the digital transmitter is segmented into multiple segments and each delay circuit in the plurality of delay circuit corresponds to a different segment of phase distortion introduced in the digital transmitter.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 14, 2019
May 26, 2020
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